Artificial shaped bodies, such as fibres, filaments, ribbons, bristles, sheets or films of plastic materials soluble in organic solvents and capable of forming films and belonging to the cellulose derivative or artificial resin types which bodies contain components having at least 10 to 12 carbon atoms in the molecule and carrying salt-forming acid groups, such components being substantially incapable of being washed-out with water (cf. Specification 459,711), are dyed with a basic dyestuff capable of forming water-soluble salts with acids and containing one or more strongly basic groups not in themselves essential to the presence of the colour. Alternatively, the material is treated with a corresponding dyestuff derivative or intermediate product, e.g. an azo coupling component, containing the strongly basic group or groups and the dyestuff is formed therefrom upon the material, e.g. by treatment, locally if desired, with a diazo component. The dyestuffs may be of the azo, di- or tri-phenylmethane, xanthene, acridine, azine, oxazine, triazine, aminonaphthalimide or indigoid classes, amino- or aminooxyanthraquinones, anthraquinonyl mercaptans or sulphides, anthraquinolines or anthrapyrimidines and may contain metal in complex union introduced before, during or after the dyeing; alternatively the materials may be preliminarily treated with a solution of the agent yielding the metal, in which case the dyestuffs of British Specification 305,648, [Class 2 (iii)], or German Specification 582,689 may suitably be applied. Preferably the dyestuffs have the strongly basic groups not directly connected to a chromogen residue. The suitable dyestuffs are of the following general formul (in which Ar represents a chromogen residue, R represents hydrogen, alkyl or substituted alkyl, R<1> represents alkyl or substituted alkyl, Alk represents alkylene, An represents a monovalent anion and <FORM:0459594/IV/1> represents pentavalent basic nitrogen, which may be linked to three residues R<1> or may form part of a pyridine ring) viz.- <FORM:0459594/IV/2> ; <FORM:0459594/IV/3> , e.g. the product obtainable by heating the azo dye, p-nitraniline --> 1 - (b -aminoethyl)aminonaphthalene, with methylisothiourea sulphate; <FORM:0459594/IV/4> e.g. the product obtainable by heating with dimethyl sulphate the azo dye obtainable by coupling with b -naphthol the diazo compound of the amine obtained by heating with dilute hydrochloric acid the thiourea from methyl isothiocyanate and the product of heating sodium p-formylaminophenolate with chlorethylamine in alcohol; <FORM:0459594/IV/5> e.g. the azo dyestuff 4-b -diethylaminoethyl-b -oxyethylaniline --> dimethylaniline; <FORM:0459594/IV/6> e.g. the product obtainable by reacting chloracetyl chloride with the azo dyestuff 4-b -oxyethylaniline --> b -naphthol and heating the product with piperidine in alcohol; <FORM:0459594/IV/7> e.g. the product obtainable as in the first step of (5) with replacement of the chloracetyl chloride by cyanamide hydrochloride; <FORM:0459594/IV/8> e.g. the product of reaction of 1 : 4-di-(g -chloro-b - oxypropylamino)anthraquinone with b - aminoethylmercaptan; <FORM:0459594/IV/9> e.g. the product of reaction of 1 : 4-di-(g -chloro-b -oxypropylamino)anthraquinone with ethylenethiourea in methylglycol; <FORM:0459594/IV/100> e.g. the product of reaction of dimethyl sulphate on the thioether from sodium methylmercaptan and 1 : 4-di-(g -chloro-b -oxypropylamino)anthraquinone; <FORM:0459594/IV/111> <FORM:0459594/IV/122> <FORM:0459594/IV/133> <FORM:0459594/IV/144> <FORM:0459594/IV/155> <FORM:0459594/IV/166> e.g. the product obtained by heating with methyl iodide in methylglycol under pressure the azo dyestuff obtainable by coupling with phenol the diazo compound of the amine obtained by reducing the nitro group of the product of reaction of m-nitraniline with methylisocyanate; <FORM:0459594/IV/17> e.g. the product obtained by heating with piperidine the azo dyestuff obtainable by coupling with b -naphthol the diazo compound of the amine obtained by hydrolysis of monobrominated p-acetylaminoacetophenone; <FORM:0459594/IV/18> e.g. the azo dyestuff, cresidine --> salicylic acid diethylaminoethyl ester; <FORM:0459594/IV/19> e.g. the product obtainable by heating 1-aminoanthraquinone-2-carboxylic acid methyl ester with excess of b -diethylaminoethylamine at 120 DEG C.; <FORM:0459594/IV/20> e.g. the product of reaction of 1-aminoanthraquinone-2-sulphochloride with b -diethylaminoethylamine in chloroform; <FORM:0459594/IV/21> e.g. azo dyestuffs from diazotized m-aminophenyltrimethylammonium or p-aminophenylpyridinium chloride or 1-aminoanthraquinonyl pyridinium compounds; <FORM:0459594/IV/22> Advantageously, the dyestuffs contain additional residues which increase the affinity for the material to be dyed and the following such residues are specified, viz. OH, <FORM:0459594/IV/23> , NO2 Alk--OH, O--Alk--OH, COOR<1>, Alk--COOR<1>, <FORM:0459594/IV/24> Various general methods of preparation of the dyestuffs are specified. The basic groups may be eliminated by hydrolysis after the dyeing or printing operation, e.g. after dyeing with the pyridinium compound from a chloracetylated p-oxyazo dye or from the 4-chloromethylbenzenesulphonic acid ester of leucothioindigo or with dyestuffs containing basic groups obtained by the action of basic substituted isocyanates or of ester chlorides of aminoalcohols, e.g. chloroformic acid-b -diethylaminoethyl ester. Level dyeing may be facilitated by the use of assistants having active cations, e.g. dodecylanine acetate, dodecyltrimethylammonium chloride or oleylaminoethylmethyldiethylammonium methosulphate or of swelling agents or hydrotropic agents, e.g. sodium tetrahydronaphthalenesulphonate. The dyeings may be fixed by after-treatment with an oxycarboxylic or oxysulphonic acid, tannin, an aluminium or other metal salt or an amine or quaternary ammonium compound of high molecular weight or may be overdyed with acid dyestuffs such as Quinoline yellow S or Alizarine direct blue A. The following examples are specified: (1) acetate artificial silk containing 10 per cent of the polymerisation product from maleic anhydride (1 mol.) and vinyl chloride (1 mol.) is dyed by treatment for 1 hour in a bath at 75 DEG C., feebly acid with acetic acid, containing the dyestuff obtained by heating 1 : 4-di-(p-oxyphenylamino) anthraquinone (1 mol.) with b -chlorethyldiethylamine hydrochloride (2 mols.) and sodium (2 mols.) in glycol monoethyl ether at 130 DEG C.; (2) acetate artificial silk containing 10 per cent of the polymerisation product from maleic anhydride (1 mol.) and vinyl chloracetate (4 mols.) is suspended for 8 hours in moist air at 80 DEG C. containing trimethylamine and is then dyed as in (1) in a bath containing sodium acetate and acetic acid with the condensation obtained by heating 1 : 4-di-(g -chloro - b - oxypropylamino) anthraquinone with an excess of morpholine in presence of fused potassium acetate and copper powder; (3) acetate artificial silk containing 10 per cent of the polymerisation product from maleic anhydride (1 mol.) and vinyl ethyl ether (1 mol.) is similarly dyed with Janus brown B; (4) the artificial silk of (1) is similarly dyed with 2 - methoxy - 6 - chloro - 9 - a - diethylamino - g -pentylaminoacridine or its monomethiodide and top dyed with Alizarine direct blue A; (5) the artificial silk of (1) is similarly dyed with 1 : 8 - diaminoanthraquinone - 4 - pyridinium chloride; (6) the artificial silk of (1) is similarly dyed with the dyestuff obtainable by reacting 5 - bromindol - 2 : 2<1> - thionaphthene indigo with pyridine in presence of aluminium chloride; (7) the artificial silk of (1) is similarly dyed with Tannin orange R; the artificial silk of (1) is similarly dyed with the condensation product obtained by heating 1-amino-4-chloranthraquinone with excess of g -dimethylamino-n-propylamine in presence of fused potassium acetate and copper acetate; (9) acetate artificial silk containing 12,5 per cent of a mixed ester containing 2,1 acetyl groups and 0,7 maleic acid residue per glucose unit is similarly dyed with the product obtained by heating the azo dyestuff from diazotized Fast red GL base and 2 - oxy - 3 - chloracetylaminonaphthalene with pyridine at 100 DEG C.; (10) acetate artificial silk containing 10 per cent of the ester acid obtained by heating with methanol the polymerisation product from maleic anhydride (1 mol.) and vinyl chloride (1 mol.) is dyed in a bath at 30 DEG C. containing acetic acid, diazotized fast GL base and the pyridinium salt from chloracetyl-2-naphthol and the dyeing is developed with a solution of sodium acetate or dilute ammonia; (11) acetate artificial silk containing 8 per cent of the polymerisation product from maleic anhydride (1 mol.) and vinyl methyl glycol ether is dyed in a bath at 30--70 DEG C. containing the product obtainable by the action of pyridine on the product of chloracetylation of the azo dyestuff, p-nitraniline --> 1-naphthol and the dyeing is fixed by treatment with a weakly ammoniacal solution of octodecyltrimethylammonium bromide. 4 - b - Diethylaminoethyl - b - oxyethylaniline is obtained by heating 4-aminophenylethyl alcohol hydrochloride (1 mol.) with benzoyl chloride (2 mols.) in benzene, saponifying the resulting dibenzoyl derivative with alcoholic soda to remove one benzoyl group, dissolving the product in a solution of sodium methylate (1 mol.), evaporating to dryness, heating the resulting alcoholate with b -diethylaminoethyl chloride in benzene and boiling with hydrochloric acid to remove the remaining benzoyl group. Chloroformic acid-b -diethylaminoethyl ester is obtained as hydrochloride by the action of phosgene on a solution of b -diethylaminoethyl alcohol in chloroform. g -Dimethylamino-n-propylamine is obtained by catalytic reduction of b -dimethylaminopropionitrile. 2 - Oxy